The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Referring now to FIG. 1, a functional block diagram of a powertrain system 100 of a vehicle is presented. The powertrain system 100 includes an engine 102 that generates drive torque to propel the vehicle. Air is drawn into the engine 102 through an intake manifold 104. A throttle valve 106 varies the volume of air drawn into the intake manifold 104. The throttle valve 106 is actuated by an electronic throttle controller (ETC) 108, which controls opening of the throttle valve 106. The air mixes with fuel provided by a fuel injector 110 to form an air and fuel mixture.
The air/fuel mixture is combusted within one or more cylinders of the engine 102, such as cylinder 112. Combustion may be initiated in any suitable manner. For example, in some engines, such as the engine 102, combustion of the air/fuel mixture is initiated by spark provided by a spark plug 114. Exhaust gas resulting from combustion is expelled from the cylinders to an exhaust system 116.
The engine 102 transfers torque to a transmission 118 through a torque converter 120. The transmission 118 may then transfer torque to one or more wheels of the vehicle. An engine control module (ECM) 130 controls torque output by the engine 102. For example, the ECM 130 may control torque output by the engine 102 based on driver inputs, such as an accelerator pedal position. A driver input module 132 provides driver inputs to the ECM 130.
Referring now to FIG. 2, an exemplary illustration of the torque converter 120 is presented. The torque converter 120 includes a turbine 122, a pump 124, and a stator 126. The pump 124 is linked to an output shaft 127 of the engine 102, and thus rotates with the output shaft 127 of the engine 102. The pump 124 includes blades or fins that direct transmission fluid within the torque converter 120 radially outward as the pump 124 turns. Directing fluid to the outside of the torque converter 120 creates a vacuum (i.e., low pressure with respect to the pressure near the outside) toward the center of the torque converter 120.
Like the pump 124, the turbine 122 includes blades or fins. The blades of the turbine 122, however, direct the transmission fluid inward from the outside of the torque converter 120. The blades of the turbine 122 are arranged such that the transmission fluid flow through the turbine 122 rotatably drives the turbine 122. The turbine 122 is connected to and drives an input shaft 128 of the transmission 118.
Referring back to FIG. 1, the torque converter 120 also includes a torque converter clutch (TCC) 134. The TCC 134 is referred to as a lock-up clutch. The TCC 134 is engaged (i.e., applied) to link the pump 124 with the turbine 122. In this manner, the TCC 134 selectively links the output shaft 127 of the engine 102 with the input shaft 128 of the transmission 118.
The TCC 134 may be controlled in any suitable manner. For example only, application of the TCC 134 may be controlled by applying a fluid or a mechanical pressure to the TCC 134. Further description of the torque converter 120 and the TCC 134 can be found in commonly assigned U.S. Pat. No. 6,695,111 issued on Feb. 24, 2004 and entitled “Torque Converter and Clutch Control” and commonly assigned U.S. Pat. No. 6,254,507 issued on Jul. 3, 2001 and entitled “Reverse One-Way Torque Converter Clutch,” the disclosures of which are incorporated herein in their entirety.